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There is a wide consensus within policy, practice, and academic circles that the adoption of modern cooking options can benefit sub-Saharan Africa. Numerous studies have examined the various demographic, socioeconomic and institutional factors affecting the adoption of clean cooking options. However, most such studies did not properly consider how geographic and environmental factors and fuel availability can affect stove adoption. In this study we use a transect-based approach, from an area of high fuelwood abundance (a state forest) to an area of high fuelwood scarcity (the semi-arid interior of Muranga county) and a peri-urban area with many fuel options (the peri-urban area of Kiambu county). We survey 400 randomly selected households along the two transects from enumeration areas used in the Kenyan national census to understand how factors intersect to affect the adoption of improved biomass stoves as primary stoves. A probit analysis suggests that stove adoption depends not only on demographic and socioeconomic factors (e.g., income, education), but also on geographical and environmental factors that reflect biomass availability and accessibility, and market access. Female-headed households tend to have lower rates of improved biomass stove adoption, largely due to lower income and related enabling factors (e.g., education, land size). Through path analysis we identify that such households can improve their opportunities to adopt improved biomass stoves through better access to credit services and participation in social groups. Overall, this study suggests the need for non-uniform and spatially explicit stove promotion strategies informed by fuelwood availability and accessibility, and market access considerations. Such strategies that are conscious of local contexts could catalyze the large-scale adoption of clean cooking options in Kenya, and elsewhere on the continent.

This study investigates the heat transfer performance of an energy efficient smokeless biomass stove enhanced by natural convection through inclined tubes. The stove incorporates a cylindrical combustion chamber (406.4 mm in diameter and 762 mm in height), enclosed within an insulated outer housing to minimize thermal losses. A mild steel inclined tube, 20–24 inches in length and positioned at a 75° inclination, facilitates passive air supply to the combustion zone via buoyancy-driven flow. Two configurations of the inclined tube were examined: a plain tube and a tube fitted with internal circular rings to induce turbulence and enhance convective heat transfer. Five K-type thermocouples were installed along the length of each tube at 120 mm intervals to monitor temperature gradients. The internally ringed tube consistently recorded wall temperatures 8–18 °C higher than those of the plain tube, attributed to intensified flow disruption and improved heat transfer from flue gases to the tube surface. This temperature rise increases the buoyancy effect, reducing the density of incoming air and thereby enhancing the natural draft into the combustion chamber. Improved air inflow promotes more efficient combustion and reduces smoke generation, without relying on mechanical assistance. The experimental results are supported by a mathematical model based on buoyant flow theory. The findings confirm that simple internal modifications to inclined tubes can substantially improve natural convection and heat transfer, making this approach a viable and low cost solution for sustainable cooking, especially in rural settings where fuel efficiency and indoor air quality are essential.

Background Indoor air pollution, including fine particulate matter (PM 2.5 ) and carbon monoxide (CO), is a major risk factor for pneumonia and other respiratory diseases. Biomass-burning cookstoves are major contributors to PM 2.5 and CO concentrations. However, high concentrations of PM 2.5 (> 1000 μg/m 3 ) have been observed in homes in Dhaka, Bangladesh that do not burn biomass. We described dispersion of PM 2.5 and CO from biomass burning into nearby homes in a low-income urban area of Dhaka, Bangladesh. Methods We recruited 10 clusters of homes, each with one biomass-burning (index) home, and 3–4 neighboring homes that used cleaner fuels with no other major sources of PM 2.5 or CO. We administered a questionnaire and recorded physical features of all homes. Over 24 h, we recorded PM 2.5 and CO concentrations inside each home, near each stove, and outside one neighbor home per cluster. During 8 of these 24 h, we conducted observations for pollutant-generating activities such as cooking. For each monitor, we calculated geometric mean PM 2.5 concentrations at 5-6 am (baseline), during biomass burning times, during non-cooking times, and over 24 h. We used linear regressions to describe associations between monitor location and PM 2.5 and CO concentrations. Results We recruited a total of 44 homes across the 10 clusters. Geometric mean PM 2.5 and CO concentrations for all monitors were lowest at baseline and highest during biomass burning. During biomass burning, linear regression showed a decreasing trend of geometric mean PM 2.5 and CO concentrations from the biomass stove (326.3 μg/m 3 , 12.3 ppm), to index home (322.7 μg/m 3 , 11.2 ppm), neighbor homes sharing a wall with the index home (278.4 μg/m 3 , 3.6 ppm), outdoors (154.2 μg/m 3 , 0.7 ppm), then neighbor homes that do not share a wall with the index home (83.1 μg/m 3 ,0.2 ppm) ( p  = 0.03 for PM 2.5 , p  = 0.006 for CO). Conclusion Biomass burning in one home can be a source of indoor air pollution for several homes. The impact of biomass burning on PM 2.5 or CO is greatest in homes that share a wall with the biomass-burning home. Eliminating biomass burning in one home may improve air quality for several households in a community.

Development of a new class of single pan high efficiency, low emission stoves, named gasifier stoves, that promise constant power that can be controlled using any solid biomass fuel in the form of pellets is reported here. These stoves use battery-run fan-based air supply for gasification (primary air) and for combustion (secondary air). Design with the correct secondary air flow ensures near-stoichiometric combustion that allows attainment of peak combustion temperatures with accompanying high water boiling efficiencies (up to 50% for vessels of practical relevance) and very low emissions (of carbon monoxide, particulate matter and oxides of nitrogen). The use of high density agro-residue based pellets or coconut shell pieces ensures operational duration of about an hour or more at power levels of 3 kWth (~12 g/min). The principles involved and the optimization aspects of the design are outlined. The dependence of efficiency and emissions on the design parameters are described. The field imperatives that drive the choice of the rechargeable battery source and the fan are brought out. The implications of developments of Oorja-Plus and Oorja-Super stoves to the domestic cooking scenario of India are briefly discussed. The process development, testing and internal qualification tasks were undertaken by Indian Institute of Science. Product development and the fuel pellet production were dealt with by First Energy Private Ltd. Close interaction at several times during this period has helped progress the project from the laboratory to large scale commercial operation. At this time, over four hundred thousand stoves and 30 kilotonnes fuel have been sold in four states in India.

Introduction: Women and children in Uganda and other low- and middle-income countries are exposed to disproportionately high levels of household air pollution from biomass smoke generated by smoke-producing cookstoves, especially in rural areas. This population is therefore particularly vulnerable to the negative health effects caused by household air pollution, including negative pregnancy outcomes and other health issues throughout life. The Midwife Project, a collaboration between research and health teams in the UK and Uganda, began in 2016 to implement an education program on lung health for mothers in Uganda, to reduce the health risks to women and children. Education materials were produced to guide midwives in the delivery of health messages across four rural health centres, and mixed-methods results of knowledge questionnaires and interviews demonstrated knowledge acquisition, acceptability and feasibility. This qualitative follow-up study aimed to improve understanding of the longer term impact of this education program from the perspective of midwives, village health team members and mothers, in consideration of rolling the program out more widely in rural Uganda. Methods: Purposive sampling was carried out to recruit consenting antenatal or postnatal women, midwives and village health team members who had been involved in an education session. Individual interviews were conducted with 12 mothers and four village health team members, and four focus groups were conducted with 10 midwives in total. Interviews and focus groups were conducted across all four health centres by two researchers and six translators as appropriate depending on language spoken (English or Lusoga). These were semistructured and directed by topic guides. Reflective and observational notes were also made. A thematic analysis was carried out by two researchers, along with production of a narrative for each mother, to enrich understanding of each individual story. Results: Midwives and village health teams had continued with the program well past the project end date and all mothers expressed making, or intending to make, changes, suggesting long-term feasibility and acceptability. Main themes generated were ability to change and changes made, ability to change dictated by money, importance of practical education, perceived health improvements, and passing on knowledge. Additional findings were that some education topics seemed to be overlooked, and there was a lack of clarity about the village health team role for the purposes of this program. Some mothers had been motivated to overcome financial barriers, for example by reconstructing cooking areas cheaply themselves. However, information given in the program about building advice and potential financial gains was inconsistent. Conclusion: Recommendations for future biomass smoke education should include explicit building advice, emphasis on financial gains, encouragement to share the knowledge acquired and clarification of the village health team role. These program changes will improve focus and relevancy, optimise impact and, with behaviour change and implementation strategy in mind, could be used for widespread rollout in rural Uganda. Future research should include quantitative data collection to objectively examine surprising perceived health benefits, including reduction in malaria and burns, and further qualitative work on why some education content appears neglected.

Indoor air pollution is ranked the 5th in the Global Burden of Disease index of the World Health Organization (WHO). Almost half of the world's population depends on biomass fuels to meet their basic energy requirements for cooking, lighting and space heating. When fuel is badly combusted in poorly designed stoves, the fuel-stove combination results in high level of noxious emissions entering the home, accumulating to dangerous levels. In this study, a Chinese unvented top lit updraft (TLUD) biomass stove was operated with three different biomass pellets formed from corn stover, cotton stalk and peanut shells. The performance tests were conducted according to the latest standard from the Chinese Ministry of Agriculture. The calorific value, moisture level, volatile matter and elemental composition are reported for each. The thermal efficiencies of the stove were 15.3%, 10.1% and 14.4%, respectively. The cooking powers were 2.68 kW, 1.61 kW and 1.57 kW. The exhaust was collected using a hood and tunnel. The CO, NO and NOX were drawn after passing 1.5 m along the tunnel and the Particulate Matter (PM) was sampled after 1.6 m. The Emission Factors (EF) for CO, NO, NOX and PM10 are reported on both a mass per unit energy delivered to the pot (g/MJNET) and a mass per mass of fuel basis (g/kg). The range for CO was 4.56-7.61 g/MJNET (11.25-21.25 g/kg); NO was 0.75-1.23 g/MJNET (2.09-3.04 g/kg); NOX was 1.13-1.90 g/MJNET (3.14-4.86 g/kg); PM10 was 0.59-0.85 g/MJNET (1.67-2.09 g/kg). The range in these values was more significantly influenced by the fuel moisture content and the percentage of volatile matter than by variations in the elemental composition.

In this study, interviewer-based questionnaires of 67 variables were administered to local fabricators and end-users of single-pot biomass stoves (SPBS) in Ghana. Additionally, two randomly selected traditional and improved SPBS were lab-tested using standard performance metrics. From the study, the relationship between fabricators and end-users was conceptualized based on selected indicators and assumptions. The study results indicated that the primary design resources for fabrication were patterns and templates, and that major challenges to fabrication were lack of training in design principles, standards and safety, poor emission efficiency and financial sustainability. Whereas end-users of improved SPBS were less affected by heat and smoke, end-users of traditional SPBS were mostly affected. From hypothesis test, because the calculated χ2cal = 24.05, and is greater than the tabulated χ2crit = 3.841, it is concluded that there is a relationship between heat, smoke effect and gender, and that female end-users of traditional SPBS were particularly affected during cooking. The traditional SPBS emitted more CO2 and CO than improved SPBS. Comparatively, 38% more end-users of traditional SPBS observed charcoal ash residue in the cooking area than improved SPBS users. Four basic practices of managing ashes from SPBS are developed. Finally, a fabricator and end-user framework are developed for energy sustainability and quality improvement.

Diese Arbeit beschäftigt sich mit den Schadstoffemissionen eines vollautomatischen Pelletkessels. Die Emissionen solcher Anlagen werden üblicherweise im stationären Volllastbetrieb, nicht jedoch während anderer Betriebsabläufe wie dem An- und Abfahren ermittelt. Es wird eine Methodik vorgestellt, mit der die Emissionen über den gesamten Zeitraum des Anlagenbetriebs ermittelt und bewertet werden. Diese Methodik wird an einem Pelletkessel angewandt. Der Einfluss transienter Vorgänge, wie An- und Abfahren, auf die emittierte Masse der Schadstoffe Feinstaub, Kohlenstoffmonoxid und Stickoxide wird dargestellt. Hierbei wird der Einfluss unterschiedlicher möglicher Betriebsarten auf das Emissionsverhalten berücksichtigt.

Household air pollution (HAP) due to solid fuel use during pregnancy is associated with adverse birth outcomes. The real-life effectiveness of clean cooking interventions has been disappointing overall yet variable, but the sociodemographic determinants are not well described. We measured personal 24-h PM2.5 (particulate matter <2.5 µm in aerodynamic diameter) thrice in pregnant women (n = 218) gravimetrically with Teflon filter, impactor, and personal pump setups. To estimate the effectiveness of owning chimney and liquefied petroleum gas (LPG) stoves (i.e., proportion of PM2.5 exposure that would be prevented) and to predict subject-specific typical exposures, we used linear mixed-effects models with log (PM2.5) as dependent variable and random intercept for subject. Median (IQR) personal PM2.5 in µg/m3 was 148 (90–249) for open fire, 78 (51–125) for chimney stove, and 55 (34–79) for LPG stoves. Adjusted effectiveness of LPG stoves was greater in women with ≥6 years of education (49% (95% CI: 34, 60)) versus <6 years (26% (95% CI: 5, 42)). In contrast, chimney stove adjusted effectiveness was greater in women with <6 years of education (50% (95% CI: 38, 60)), rural residence (46% (95% CI: 34, 55)) and lowest SES (socio-economic status) quartile (59% (95% CI: 45, 70)) than ≥6 years education (16% (95% CI: 22, 43)), urban (23% (95% CI: −164, 42)) and highest SES quartile (−44% (95% CI: −183, 27)), respectively. A minority of LPG stove owners (12%) and no chimney owner had typical exposure below World Health Organization Air Quality guidelines (35 μg/m3). Although having a cleaner stove alone typically does not lower exposure enough to protect health, understanding sociodemographic determinants of effectiveness may lead to better targeting, implementation, and adoption of interventions.

A large body of evidence has confirmed that the indoor air pollution (IAP) from biomass fuel use is a major cause of premature deaths, and acute and chronic diseases. Over 78% of Sri Lankans use biomass fuel for cooking, the major source of IAP in developing countries. We conducted a review of the available literature and data sources to profile biomass fuel use in Sri Lanka. We also produced two maps (population density and biomass use; and cooking fuel sources by district) to illustrate the problem in a geographical context. The biomass use in Sri Lanka is limited to wood while coal, charcoal, and cow dung are not used. Government data sources indicate poor residents in rural areas are more likely to use biomass fuel. Respiratory diseases, which may have been caused by cooking emissions, are one of the leading causes of hospitalizations and death. The World Health Organization estimated that the number of deaths attributable to IAP in Sri Lanka in 2004 was 4300. Small scale studies have been conducted in-country in an attempt to associate biomass fuel use with cataracts, low birth weight, respiratory diseases and lung cancer. However, the IAP issue has not been broadly researched and is not prominent in Sri Lankan public health policies and programs to date. Our profile of Sri Lanka calls for further analytical studies and new innovative initiatives to inform public health policy, advocacy and program interventions to address the IAP problem of Sri Lanka.